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Material for scrubbing Cu-clad boards

Discussion in 'Electronic Design' started by pimpom, Mar 16, 2010.

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  1. pimpom

    pimpom Guest

    This is for those of you who are making their own PCBs for hobby,
    prototyping and low-volume production.

    I've seen things like fine sandpaper and steelwool recommended on
    hobbyist websites for cleaning copper-clad boards prior to
    transferring the pattern and etching. 40 years ago, I used wood
    ash. It worked quite well but wasn't always readily available.
    Then I tried tooth powder as it's more abrasive than toothpaste.
    It sort of worked, but required too much scrubbing. Then I got
    the idea of using household scrubbing powder. It works fast,
    having just the right amount of abrasive property with no danger
    of inflicting deep scratches. Vim and Biz are two popular Indian
    brands.

    I feel no need to look for a better material, but I'm curious
    about what others are using.
     
  2. Gerard Bok

    Gerard Bok Guest

    It has been quite a while, but in the old days I used Seno
    Polyblock. That is (or was) a kind of big (matchbox sized) crayon
    eraser, specially made to clean Cu plating.
    http://www.hamers.de/en/electronics/print6.php
    shows a picture.
     

  3. The acid is going to eat it off of ALL the unmasked areas and a little
    tarnish wont stop it. I think abrasive scrubbing was overkill this whole
    time.
     
  4. Hammy

    Hammy Guest

    I use 400grit or finer sandpaper lightly and I don't get deep grooves.
    I suppose for RF you would want a very light abrasive so as to keep
    the cooper uniform. This assumes the board itself already has uniform
    copper distribution. I doubt that most general purpose boards have
    precision distribution .
     
  5. Gerard Bok

    Gerard Bok Guest

    Acid ?
    I use Polyblock to remove the photolayer.
    That is after the etching process :)
     
  6. GregS

    GregS Guest

     
  7. GregS

    GregS Guest

    That should also get rid of oils with a little aggitation.
     
  8. pimpom

    pimpom Guest

    But FeCl3 has a hard time eating through grease and finger
    smudges. I always have a stack of 12"x12" copper-clads in stock
    and some of them go through a lot of handling and shuffling
    before it's their turn to be used. And since it's best to remove
    any tarnish anyway before soldering, scrubbing followed by a
    thorough rinsing in running water ensures a smooth process.
     
  9. pimpom

    pimpom Guest

    I was really talking about pre-etch cleaning.
     
  10. pimpom

    pimpom Guest

    I suppose not. I'm not really concerned about that, but it's nice
    to know that individual particles of the scouring powder are not
    hard enough to score deeply into the copper. What I didn't
    mention earlier was that I keep board and powder wet while
    scrubbing. A level teaspoonful of powder is more than enough to
    get a palm-sized board sparkling clean without any visible nicks
    and scratches, and it takes under a minute of mild scrubbing
    unless the board is heavily tarnished.
     
  11. pimpom

    pimpom Guest

    I tried using the green pad too, but I really prefer scrubbing
    with my fingers. Of course, I wouldn't recommend it for mass
    production!
    I sometimes do the pre-etch (brief dipping) too, but somehow I
    don't have the patience to make it a regular practice. No logic
    here as I'm normally a very patient type.
     
  12. Artemus

    Artemus Guest

    Kleen King worked like a champ for me.
    Art
     
  13. NEVR-DULL tarnish removal wadding will aid in getting the stuff scrubbed
    off too. Also a very good pre-prep for the HASL to follow.
     
  14. D from BC

    D from BC Guest

    Yup..That's what I use. Or whatever generic synthetic scouring pad I can
    get.

    In the past I've tried Rag with abrasive( Vim, toothpaste, baking
    soda),400 grit wet sanding paper, copper wool and steel wool.
     
  15. Joe

    Joe Guest

    He probably is in or near Tripura, Mizoram, or Manipur,
    some Indian States that are 300-500 Km east of Kolkata.
     
  16. Tim Watts

    Tim Watts Guest

    I've used those blocks after etching to get nice bright copper prior to a
    quick spray of hobby grade conformal coating. 000 grade (super fine) steel
    wool would be OK too, as long as you wash all the strands off afterwards.
     
  17. It depends on the acid. Ferric chloride, which is popular among
    hobbyists, is stopped even by a fingerprint.

    If you use toner transfer, it is essential that the copper is clean,
    otherwise the toner will not stick reliably.
     
  18. pimpom

    pimpom Guest

    That's right. I'm in Aizawl, Mizoram.
     

  19. A laser printer prints on both conductive and non-conductive surfaces,
    but you want clean copper because you want the resist directly on the
    copper, not on a fingerprint.
     
  20. Guest

    Neat, India to the East of Bangladesh.
     
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